Which event terminates protein synthesis?

Which event terminates protein synthesis?

• A. Initiation
• B. Stop codon
• C. Elongation
• D. Promoter binding

Answer: (B)

Protein synthesis ends when the ribosome reaches a stop codon on the mRNA. Stop codons (UAA, UAG, UGA) do not code for amino acids, and there’s no tRNA with a matching anticodon to add one. Instead, release factors recognize the stop codon, triggering the release of the newly made polypeptide and the disassembly of the ribosome. This termination step ensures the protein is released rather than continued elongation. For context, initiation starts translation, elongation adds amino acids, and promoter binding is part of transcription, not translation, so they don’t terminate the process.

Protein synthesis ends when the ribosome reaches a stop codon on the mRNA. Stop codons (UAA, UAG, UGA) do not code for amino acids, and there’s no tRNA with a matching anticodon to add one. Instead, release factors recognize the stop codon, triggering the release of the newly made polypeptide and the disassembly of the ribosome. This termination step ensures the protein is released rather than continued elongation. For context, initiation starts translation, elongation adds amino acids, and promoter binding is part of transcription, not translation, so they don’t terminate the process.